Ukraine has launched the largest drone offensive on Moscow of the full-scale war, in an attack that damaged a key oil refinery, caused fires, and sent debris raining down across the region.

Air defenses shot down at least 194 drones bound for the Russian capital overnight into Thursday, according to Moscow Mayor Sergei Sobyanin. That’s far higher than other days of heavy attacks in recent months, when drones only numbered in the double digits.

The barrage was part of a larger Ukrainian attack over a broad swath of Russia, with air defenses intercepting 555 drones, according to the Russian Ministry of Defense – including over the Sea of Azov.

Flights at all major Moscow airports were temporarily suspended on Thursday, Reuters reported, citing the Russian aviation agency.

Kyiv has been stepping up its targeting of Russian energy infrastructure in long-range attacks in recent weeks, which Ukrainian President Volodymyr Zelensky has framed as a key strategy in forcing Moscow to end the war.

Zelensky called Thursday’s attacks “a fully justified response to Russian strikes on our cities and communities,” in a Telegram post from Brussels, where he arrived yesterday for meetings with NATO leaders.